8.3 Resource Group - Content

Represents a defined collection of entities that may be discussed or acted upon collectively but which are not expected to act collectively, and are not formally or legally recognized; i.e. a collection of entities that isn't an Organization.

8.3.1 Scope and Usage

8.3.1.1 Use Cases

The Group resource is used in one of two ways:

To define a group of specific people, animals, devices, etc. that is being tracked, examined or otherwise referenced as part of healthcare-related activities

To define a set of possible people, animals, devices, etc. that are of interest for some intended future healthcare-related activities

Examples of the former could include group therapy or treatment sessions, exposed entities tracked as part of public health, etc. The latter might be used to define expected subjects for a clinical study.

Both use cases are handled by a single resource because the data elements captured tend to be similar.

8.3.2 Boundaries and Relationships

There are a number of mechanisms in FHIR for communicating collections of resources:

The List resource - enumerates a flat collection of resources and provides features for managing the collection.
While a particular List instance may represent a "snapshot", from a business process perspective the notion of "List"
is dynamic – items are added and removed over time. The List resource references other resources. Lists may be
curated and have specific business meaning.

This Group resource - defines a group of specific people, animals, devices etc. by enumerating them,
or by describing qualities that group members have. The group resource refers to other resources, possibly implicitly.
Groups are intended to be acted upon or observed as a whole; e.g. performing therapy on a group, calculating risk for a group,
etc. This resource will commonly be used for public health (e.g. describing an at-risk population), clinical trials (e.g.
defining a test subject pool) and similar purposes.

CareTeam. Group is distinct from CareTeam. Group is patient-independent and identifies an
undifferentiated set of individuals who are intended to be the target of one or more clinical activities (e.g. set of
clinical trial participants, set of individuals impacted by or at risk of a public health event, a herd or flock, etc.)
The CareTeam resource establishes a set of relationships and roles and is specific to a particular Patient.
The actors are the individual members or organized group of individuals. CareTeam can be referenced by EpisodeOfCare,
Encounter, or CarePlan to identify the set of individuals (and their respective roles) who are intended to be involved
in providing the care defined by those resources.

The Bundle resource - is an infrastructure container for a group of resources. It does not have narrative
and is used to group collections of resources for transmission, persistence or processing (e.g. messages, documents, transactions,
query responses, etc.) The content of bundles is typically algorithmically determined for a particular exchange or persistence purpose.

The Composition resource - defines a set of healthcare-related information that is assembled
together into a single logical document that provides a single coherent statement of meaning, establishes its own context and
that has clinical attestation with regard to who is making the statement. The composition resource provides the basic structure
of a FHIR document. The full content of the document is expressed using a bundle. Compositions will
often reference Lists as the focus of particular sections.

The DomainResource.contained element - allows multiple resources to be nested
inside any DomainResource. This is a special type of grouping where the grouped resources lose independent existence - they
no longer have their own identifiers, can't easily be queried independently, etc. Use of this grouping is a technical
mechanism for managing the independence of resources and has no impact on meaning.

Contained, bundled and remotely referenced
resources convey the same meaning.

8.3.3.2 Constraints

8.3.3.3 Mixing Characteristics and Members

If both Group.characteristic and Group.member are present, then the
members are the individuals who were found who met the characteristic. It's possible that
there might be other candidate members who meet the characteristic and aren't (yet) in the list.
All members SHALL have the listed characteristics.

8.3.4 Search Parameters

Search parameters for this resource. The common parameters also apply. See Searching for more information about searching in REST, messaging, and services.